Australian researchers get closer to scalable quantum computing

Researchers in Australia are making progress in their quest to construct a scalable quantum computer, having developed a method for extracting information from an electron racing around a phosphorus atom in silicon, the MIT Technology Reviewreported Wednesday. The achievement suggests that commercial use — and, therefore, wider implementation of a probabilistic computing model much faster than current systems — could be just a wee bit closer.

The idea of a operating a quantum computer with a quantum bit — or qubit — based on a phosphorous atom harks back to a vision articulated by Australian Bruce Kane in research published in Nature in 1998. “The realization of such a computer is dependent on future refinements of conventional silicon electronics,” Kane explained in the abstract to his paper. Researchers in Australia have been striving to put Kane’s concept into practice for more than 10 years, the MIT Technology Review article notes, and their latest step is to get information from an agitated electron:

These guys implanted a single phosphorous atom in a silicon nanostructure and placed it in a powerful magnetic field at a temperature close to absolute zero. They were then able to flip the state of an electron orbiting the phosphorous atom by zapping it with microwaves.

The final step, a significant challenge in itself, was to read out the state of the electron using a process known as spin-to-change conversion.

The end result is a device that can store and manipulate a qubit and has the potential to perform two-qubit logic operations with atoms nearby; in other words the fundamental building block of a scalable quantum computer.

Still, the Australians have work to do, according to their paper, which they submitted on Monday:

Future experiments will focus on the coupling of two donor electron spin qubits through the exchange interaction, a key requirement in proposals for scalable quantum computing architectures in this system. Taken together with the single-atom doping technologies now demonstrated in silicon, the advances reported here open the way for a spin-based quantum computer utilising single atoms, as first envisaged by Kane more than a decade ago.

Meanwhile, researchers in England have done work of their own on quantum entanglement involving phosphorus atoms.

Quantum computers from Canada have seen some commercial adoption, with Lockheed Martin and a Google-initiated lab signing up for D-Wave Systems quantum computers. If competitors from England and Australia come onto the scene, further innovation could follow and cause prices to fall.